Field of the Invention
This invention is related to a composition and method of using non-molybdate corrosion inhibitors in sterilizing applications.
Description of Related Art
Food and beverages packaged in cans needs to be sterilized or pasteurized prior to being sold. The food industry normally uses high temperatures to kill microorganisms and preserve the packed food and beverages. Heat preservation of food and beverages covers a range of process water temperatures of 30-150° C. During the sterilization process, food and beverage cans are first heated with hot process water at approximately 120-140° C., and then cooled down by contacting the cans with cooling process water, typically at room temperature. For pasteurization the temperature level is lower with a range of 30-90° C. The cooling process water is often treated with oxidizing biocides such as chlorine and bromine to reduce the risk for re-infection of the cans containing food and beverages. The process water normally has a pH range of 7.5-9.0, and a calcium hardness range of 5-500 ppm as CaCO3, total hardness ranges from 10-800 ppm as CaCO3, m-alkalinity ranges from 5-500 ppm as CaCO3 and chloride ranges from 5-500 ppm. Typically, the water chemistry tends to exhibit lower hardness and lower pH conditions, which makes the water more corrosive. Therefore, the cans and sterilizing equipment need more corrosion protection.
Conventional sterilizing and pasteurizing solutions utilize molybdate, nitrite and zinc as corrosion inhibitors. However, these inhibitors are not environmentally friendly, and have been banned for use in some countries. In addition, molybdate salts are quite expensive. Accordingly, there is a need for a composition that uses non-molybdate corrosion inhibitors for sterilizing and pasteurizing applications and that is more environmental friendly.
The current invention provides for a composition and method of using non-molybdate corrosion inhibitors in sterilizing and pasteurizing applications. Further, the disclosed composition has better performance than the conventional molybdate containing sterilizing products, especially at low hardness, low pH and high chloride conditions and is environmentally friendly.